The overall objectives of this research project are to describe and understand how physicians' attitudes toward major issues in the organization and delivery of health care develop, how they vary among different segments of the profession, and how they change. The purpose of this renewal grant application is to continue and extend our present research, specifically: 1. To complete and report the analysis of interview and mail questionnaire data from New York State private practitioners at four points in time between 1964 and 1970 and from national samples of physicians, including interns and residents (housestaff), and medical students, in 1973. 2. To reinterview subsamples of medical practitioners in the 1973 national sample at three points in time during the legislative history of National Health Insurance (NHI): immediately after its passage by the House of Representatives, after the bill becomes law, and ten to twelve months after its passage. The principal aims of the reinterviews are a) to study the effects of NHI legislation on physicians' attitudes, and in doing so, test the hypothesis that perceptions of legitimacy and fait accompli are mechanisms that explain such effects and b) to study the more general question of under what conditions laws influence attitudes and behavior, by comparing the effects on physicians' attitudes and behavior of Medicare, Medicaid, NHI, and Professional Standards Review Organizations (PSROs).